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RE: Fixed File Cabinet - Dead Load or Li

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Eric,

Let first say that my previous posts were based upon my opinion (i.e. how
I would do it).  Based upon your further description of the "file
cabinet", it does sound like you are talking about high density file
storage.  I have ALWAYS treated such as a live load.

Having said that, if the ASCE 7 code does not expressly state somewhere
that high density storage (or some other item) must be considered a live
load, then it typically would be at the discretion of the engineer of
record.  Ultimately, in seems that it may come down to what level of risk
you are willing to take or how "sure" you are about the magnitude of the
loads from the high density storage.  Are you "1.2" sure (the factor for
dead loads) or are you "1.6" sure?  Since you asked the question even
though you seem to have a pre-conceived idea of what the answer should be,
it seems to me that you are not really ready to take the "risk" that you
are "1.2" sure.

If it helps, I will further expand on my opinions.  You imply that ASCE 7
states that a bridge crane can be considered a dead load.  To be honest, I
find that a little hard to believe, but I am willing to take your word on
it (since I don't have the initiative to look it up at the moment).
Regardless, I know that _I_ treat the weight of the bridge crane equipment
as a live load.  After all, there is nothing in any code that says I can't
take a more severe approach.  My reasoning is that when I have design
structural systems that support a bridge crane, I typically don't know
what manufacturer will be supplying the crane (unless the owner decides to
specify that up front).  Since the weight of the bridge crane equipment
can vary from manufacturer to manufacturer, the gravity load due to that
equipment has a fairly high degree of uncertainty (the weights can vary
significantly).  As a result, I feel that it should be a live load.

I take a similar approach to mechanical equipment and electrical swtich
gear, etc, except the variation of the weights from manufacturer to
manufacturer can even be greater.  So, I treat all mechanical equipment
and electrical equipment as live loads.  I will include an "allowance"
(usually conservative) for typical duct work, electrical conduit, and
small piping (not large steam lines or main water lines) in the dead load.

As far as you situation, if you decide that you feel comfortable with
including the weight of the high density storage equipment (not the actual
storage items) in the dead load, then DEFINITELY do not include the weight
of the storage material in that.  You might be able to determine that
maximum load of the stored material based upon an assumption that it will
all be paper, but what happens if something other than paper gets stored
on the units?  Keep in mind that some high density storage is used to
store X-ray films.  Such a situation can result in a load MUCH heavier
than if paper is stored.  The end result is that you might be rather sure
about the weight of the "file cabinet" itself, but you can never be sure
about the weight of the contents.

Again, the end result for me is that if I were in your shoes, I would
consider it live load.

HTH,

Scott
Ypsilanti, MI


On Tue, 23 Jul 2002, Eric Green wrote:

> If my 20'x12', 40,000 pound file cabinet ends up in the bunched in the corner, I am in trouble regardless. I think it is more likely the a/c is going to end up being moved :-).
> 
> I should explain, this is a filing system that rolls on structural tracks, like train tracks, that are bolted to the floor. This thing is pretty big and cannot be casually moved. The installers are pretty sophisticated, which is why they hire guys like me to tell them if it is ok to install them. They know they are very heavy and frequently require upgrades to the floor system. I think the closest system this can be compared ot is a bridge crane (yes, it is a rough analogy).
> 
> eric green
> -speaking for me, not my employer
> 
> -----Original Message-----
> From: Christopher Wright [mailto:chrisw(--nospam--at)skypoint.com]
> Sent: Tuesday, July 23, 2002 11:24 AM
> To: ?
> Subject: RE: Fixed File Cabinet - Dead Load or Li
> 
> 
> >The question of LL vs DL seems to me to be one of probability.
> I think it's a matter of the dynamic nature of the load consequently the 
> possibility of amplification, the possibility of re-location and the 
> likelihood that it's repetitive and a possible source of fatigue. 
> 
> >I do not see much difference between a rolling file cabinet and a large 
> >a/c compressor or air handler (which ASCE clearly indicates is a dead load).
> The difference is that one rolls and the other doesn't. The A/C isn't 
> going to end up bunched in a corner somewhere with a lot of other units 
> when someone re-models the space or replaces carpets.
> 
> Christopher Wright P.E.    |"They couldn't hit an elephant at
> chrisw(--nospam--at)skypoint.com        | this distance"   (last words of Gen.
> ___________________________| John Sedgwick, Spotsylvania 1864)
> http://www.skypoint.com/~chrisw
> 
> 
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